On Fri, 6 Mar 2026 14:43:36 +0800 Baolin Wang <baolin.wang@linux.alibaba.com> wrote:
> This is a follow-up to the previous work [1], to support batched checking
> of the young flag for MGLRU.
>
> Similarly, batched checking of young flag for large folios can improve
> performance during large-folio reclamation when MGLRU is enabled. I
> observed noticeable performance improvements (see patch 5) on an Arm64
> machine that supports contiguous PTEs. All mm-selftests are passed.
Thanks, I updated mm-new with this.
> Changes from v2:
> v2: https://lore.kernel.org/all/cover.1772185080.git.baolin.wang@linux.alibaba.com/
> - Update the commit message of patch 5 (per David).
> - Fix some coding style issues (per David).
> - Remove 'cur_pte' variable in lru_gen_look_around() (per David).
> - Move 'ptes += nr;' to the suitable place in folio_referenced_one() (per David).
> - Add acked tag from David. Thanks.
>
Here's how v3 altered mm.git:
include/linux/pgtable.h | 3 +--
mm/rmap.c | 2 +-
mm/vmscan.c | 11 +++++------
3 files changed, 7 insertions(+), 9 deletions(-)
--- a/include/linux/pgtable.h~b
+++ a/include/linux/pgtable.h
@@ -1124,8 +1124,7 @@ static inline int clear_flush_young_ptes
* Returns: whether any PTE was young.
*/
static inline int test_and_clear_young_ptes(struct vm_area_struct *vma,
- unsigned long addr, pte_t *ptep,
- unsigned int nr)
+ unsigned long addr, pte_t *ptep, unsigned int nr)
{
int young = 0;
--- a/mm/rmap.c~b
+++ a/mm/rmap.c
@@ -964,7 +964,6 @@ static bool folio_referenced_one(struct
pte_t pteval = ptep_get(pvmw.pte);
nr = folio_pte_batch(folio, pvmw.pte, pteval, max_nr);
- ptes += nr;
}
if (lru_gen_enabled() && pvmw.pte) {
@@ -982,6 +981,7 @@ static bool folio_referenced_one(struct
WARN_ON_ONCE(1);
}
+ ptes += nr;
pra->mapcount -= nr;
/*
* If we are sure that we batched the entire folio,
--- a/mm/vmscan.c~b
+++ a/mm/vmscan.c
@@ -4201,7 +4201,6 @@ bool lru_gen_look_around(struct page_vma
struct lruvec *lruvec;
struct lru_gen_mm_state *mm_state;
unsigned long max_seq;
- pte_t *cur_pte;
int gen;
lockdep_assert_held(pvmw->ptl);
@@ -4247,10 +4246,10 @@ bool lru_gen_look_around(struct page_vma
pte -= (addr - start) / PAGE_SIZE;
- for (i = 0, addr = start, cur_pte = pte; addr != end;
- i += nr, cur_pte += nr, addr += nr * PAGE_SIZE) {
+ for (i = 0, addr = start; addr != end;
+ i += nr, pte += nr, addr += nr * PAGE_SIZE) {
unsigned long pfn;
- pte_t ptent = ptep_get(cur_pte);
+ pte_t ptent = ptep_get(pte);
nr = 1;
pfn = get_pte_pfn(ptent, vma, addr, pgdat);
@@ -4264,11 +4263,11 @@ bool lru_gen_look_around(struct page_vma
if (folio_test_large(folio)) {
const unsigned int max_nr = (end - addr) >> PAGE_SHIFT;
- nr = folio_pte_batch_flags(folio, NULL, cur_pte, &ptent,
+ nr = folio_pte_batch_flags(folio, NULL, pte, &ptent,
max_nr, FPB_MERGE_YOUNG_DIRTY);
}
- if (!test_and_clear_young_ptes_notify(vma, addr, cur_pte, nr))
+ if (!test_and_clear_young_ptes_notify(vma, addr, pte, nr))
continue;
if (last != folio) {
_